diff --git a/src/uploader.c b/src/uploader.c
index 5811716..05aec21 100644
--- a/src/uploader.c
+++ b/src/uploader.c
@@ -1277,13 +1277,13 @@ static void prepare_frame(uv_work_t *work)
     char read_data[AES_BLOCK_SIZE * 256];
     memset_zero(read_data, AES_BLOCK_SIZE * 256);
     unsigned long int read_bytes = 0;
-    unsigned long int total_read = 0;
+    uint64_t total_read = 0;
 
     do {
         if (state->canceled) {
             goto clean_variables;
         }
-        
+
         read_bytes = pread(fileno(state->original_file),
                            read_data, AES_BLOCK_SIZE * 256,
                            shard_meta->index*state->shard_size + total_read);